It's a ... of cake.
It's a piece of cake.
It's a ... in disguise.
It's a blessing in disguise.
The ball is in your ....
The ball is in your court.
Let ... dogs lie.
Let sleeping dogs lie.
A leopard can't ... its spots.
A leopard can't change its spots.
It's a ... in the bucket.
It's a drop in the bucket.
Take it with a ... of salt.
Take it with a grain of salt.
The best thing since ... bread.
The best thing since sliced bread.
It's the ... of both worlds.
It's the best of both worlds.
Bite off more than you can ....
Bite off more than you can chew.
You're ... up the wrong tree.
You're barking up the wrong tree.
Once in a ... moon.
Once in a blue moon.
Don't put all your eggs in one ....
Don't put all your eggs in one basket.
She's a ... horse.
She's a dark horse.
Kill ... birds with one stone.
Kill two birds with one stone.
Burn the ... oil.
Burn the midnight oil.
Cross that ... when you come to it.
Cross that bridge when you come to it.
Sit on the ....
Sit on the fence.
Let's ... the knot.
Let's tie the knot.
I ... a rat.
I smell a rat.
As ... as a rock.
As solid as a rock.
Actions ... louder than words.
Actions speak louder than words.
At the ... of a hat.
At the drop of a hat.
... the hook.
Off the hook.
... the hatchet.
Bury the hatchet.
Every cloud has a ... lining.
Every cloud has a silver lining.
Curiosity ... the cat.
Curiosity killed the cat.
I'll be glad to see the ... of him.
I'll be glad to see the back of him.
Close, but no ....
Close, but no cigar.
Feeling ... the weather.
Feeling under the weather.
... on the bandwagon.
Jump on the bandwagon.
... your tongue.
Bite your tongue.